[HN Gopher] 1D Chess
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1D Chess
Author : burnt-resistor
Score : 587 points
Date : 2026-04-10 15:37 UTC (7 hours ago)
(HTM) web link (rowan441.github.io)
(TXT) w3m dump (rowan441.github.io)
| naorz wrote:
| Fun stuff, love it!
| tkapin wrote:
| Nice! :)
| schmeichel wrote:
| Finally, a version of Chess I can understand. Thank you.
| asibahi wrote:
| This is really nice.
|
| Incidentally, there is an actual 1D game that is one of the most
| popular games on the planet: Backgammon.
| zniturah wrote:
| Good observation. Considering stacking of pieces maybe 1.5D
| though.
| a3w wrote:
| Chess has different pieces, which has higher entropy than a
| true 1d backgammon or 1d checkers with only one piece a
| field.
|
| You could play with pieces that have a value of 1..N instead.
| Starting with 2,3, and 5 value pieces, and splitting them as
| needed. Making it one-dimensional again, while keeping 100%
| of the rules.
|
| Final verdict, therefore: backgammon is 1D, not 1.5.
|
| We could pretend that the second dimension was not playing a
| role in tactics back then, since it was very recently
| invented, like the brothers Wright invented the third
| dimension a hundred years ago. Or some hot air balloon at a
| world faire did it.
| traderj0e wrote:
| The "dimensions" in these board games isn't a
| mathematical/topology thing, is it? Normally one dimension
| = one real number space. Every board game ever would fit in
| 1D then, "2D" chess included.
|
| I'm fine calling Backgammon 1.5-D. Physically you focus on
| a single dimension, and the second one matters too but it's
| not the same.
| highphive wrote:
| That's a good point, you could surely model full chess in
| a single dimension, it would just be that each pieces'
| movement rules would be more confusing
|
| E.g. a pawn can move exactly 8 squares towards its
| opponents end (16 on its first move if no piece occupies
| 8 squares away), but can only capture 7 or 9 squares
| forward (with some extra modulo math to prevent wrapping)
| moffkalast wrote:
| Backgammon, the game everyone's seen and at the same time
| nobody knows how to play :P
| Sharlin wrote:
| I learned to play backgammon because it was one of the three
| games on my Nokia phone circa 2001 :P
| dhosek wrote:
| My brother and I once took a train trip from L.A. to Omaha
| and back for a friend's wedding and played backgammon for
| most of the trip. For weeks afterwards, I saw backgammon
| everywhere (most notably when reading dialogue-heavy books
| with lots of 1-line paragraphs).
| traderj0e wrote:
| Solitaire and Hearts too. Well I actually know and love
| Hearts, but most people seem to know it as "that game in
| Windows where you play random cards"
| etskinner wrote:
| Mancala is roughly 1D too!
| pessimizer wrote:
| There are tons of 1D games. Somebody else mentioned Mancala,
| and I'd also mention the venerable Game of Goose, which can
| become anything from Candyland to sophisticated things like
| Kramer and Kiesling's That's Life or Parlett's Hare & Tortoise.
| Hell, Monopoly is also 1D if we're willing to allow circuits
| like Mancala.
| sieste wrote:
| It took me an embarrassing number of attempts to win.
| bbx wrote:
| Oh very interesting. Even with these restrictions, there are
| quite a few variations, and it seems only one ends up with white
| winning.
| lschueller wrote:
| Cool idea. This is smart and lean. I like it
| tintor wrote:
| The first move is always: white rook takes black rook, then the
| only remaining move for black is to move the knight away, which
| results in checkmate.
| nippoo wrote:
| If you play the game, you realise this ends up in stalemate.
| Fabricio20 wrote:
| I'm not very good at chess, but I dont get why most things
| are considered a stalemate? I strategically remove all pieces
| of the enemy, leaving only the king against my rook/tower
| whatever its called, the king has nowhere to run. In my eyes
| it's a checkmate. The game just calls it a stalemate. Would
| be a stalemate if I couldn't do anything, but I can kill the
| enemy king.
| al_borland wrote:
| It's a stalemate because while the king can't move, he
| isn't under active attack. There is nowhere he can legally
| move, but he's safe where he's at.
| jandrese wrote:
| That rule caught me up too. In regular chess if it is
| your opponents turn and their only pieces are a king in
| the 1,8 square and a pawn that is pressed up against one
| of your pawns and you have rooks in the 2,1 and 8,7
| squares that counts as a victory does it not?
| umanwizard wrote:
| No. That is a draw assuming it is the player with only a
| king's turn to move.
|
| Translating your notation to normal chess notation:
|
| White king on h1, black rooks on a2 and g8, black king in
| some random other place, white to move.
|
| That is a draw, because white is NOT in check, but has no
| legal moves. That scenario is called stalemate. If white
| were in check, it would be checkmate and a win for black.
| Set it up on any chess analysis board website and it will
| say the game is a draw.
| tshaddox wrote:
| But why? That feels like a victory.
| asibahi wrote:
| Because that's the rule. There doesn't have to be a
| rational reason.
| lamasery wrote:
| ... and if it _weren 't_ the rule, it'd make a lot of
| mid- and late-game play much safer for the player with
| the advantage. As it is, it's something they have to
| watch out for, which constrains them somewhat. You have
| to win, but not the _wrong way_ , and your opponent can
| attempt to force you to "win" the "wrong way" (resulting
| in a stalemate).
| rokkamokka wrote:
| There is an explanation further down. A stalemate is if the
| enemy has no valid loves and is not in check
| umanwizard wrote:
| Black can't move the knight: it's illegal to make a move that
| puts yourself in check. Thus black has no legal moves, but
| isn't in check, so the result is a draw.
| vladde wrote:
| i could not beat it, and i can't read that chess notation
| DrammBA wrote:
| the notation is just an array of move tuples, each tuple
| contains 1 move for white and 1 move for black, where each move
| is written as <1st letter of piece name><destination square>
| thesuitonym wrote:
| The letter is the piece to move, and the number is the index to
| move to, starting from 1 on the left. The first alphanumeric
| pair is your move, then the computer's move. Comma. Your move,
| computer's move...
| qup wrote:
| The first move after the comma is yours (open with kNight to
| 4), and the second move is apparently predetermined or always
| chosen.
| burnt-resistor wrote:
| There's a coordinate-based solution in the source code issues.
| I couldn't elucidate that notation either.
|
| https://github.com/Rowan441/1d-chess/issues/1
|
| Edit: There's a second solution where instead of moving the
| rook back 2, move the king forward one and the take the black
| knight with the rook as the checkmate move.
| northfield27 wrote:
| Haha, i was taking N4 and N6, but didn't figure the steps after
| that.
|
| To win we need to let knight die because rook can move multiple
| steps to kill the king.
|
| From a third person perspective R2 is a deceptive move that takes
| advantage algorithm to make the black king back off to kill its
| knight.
| aNapierkowski wrote:
| you could also just move your king on that move same result
| knight cant move, only king can, so it has to back away
| palata wrote:
| It was a lot more fun than I first thought!
| quuxplusone wrote:
| Mentioned in TFA: This version of chess is given by Martin
| Gardner in his "Mathematical Games" column of July 1980 (pages 27
| and 31) -- https://www.jstor.org/stable/24966361 -- and the
| analysis of White's mate is given in the column of August 1980
| (page 18) -- https://www.jstor.org/stable/24966383.
|
| I do wonder how things would change if the board were 9 cells
| long; 10 cells long; etc. Also, it seems "in the spirit" to
| permit castling if neither K nor R has moved yet: i.e., from the
| position
|
| K _ R N r _ n k
|
| White ought to be permitted to
|
| _ R K N r _ n k
|
| (Or maybe there's a stronger argument for R K _ N r _ n k,
| actually. The former was conceptually "rook moves halfway toward
| king, then king moves to the other side of rook"; but the latter
| is "rook moves two steps in king's direction while king moves to
| the other side of rook.")
|
| I'm pretty sure this wouldn't change the analysis on the 8-cell
| board at all, though. I wonder if it would change the analysis on
| any size of board.
| al_borland wrote:
| Maybe I'm not good enough at chess to understand the strategy
| here, but how would castling be useful in this 1-D game?
| Castling in a normal game protects your King and activates the
| Rook. In this 1-D game, your King starts out protected behind
| the Rook. If you castle and end up in a _ R K N position, your
| king is exposed and your Rook is trapped behind the King,
| useless, with no way to ever get it back out. The Rook seems
| essential for mate, and its power has been eliminated.
| teiferer wrote:
| Exactly. Feels like R K N would be a more suitable initial
| position in which castling would swap the king into safety,
| provided it has not moved and is not in check...
|
| Though maybe in that case the best first move for both is to
| castle and we are non the wiser (back to the original
| starting position)
| kkaske wrote:
| I was only able to beat this after a couple retries. The hint was
| hard to read.
| gef wrote:
| Reminds me of Edwin A. Abbott's Flatland, where he describes
| Lineland. A one-dimensional world whose King can only move
| forward and backward, cannot conceive of sideways, and considers
| his tiny segment of existence complete and sufficient. The
| Linelanders are portrayed as pitiable, intellectually imprisoned
| by their single dimension. Much like us in our three :)
| rOOmbambar9 wrote:
| It's very interesting and fun!)
| juleiie wrote:
| That finally confirmed that I am too regarded for chess if even
| 1D is too hard yay
| amrrs wrote:
| is that str.replace(g,t) ?
| juleiie wrote:
| No. I am actually too highly regarded for measly single
| dimensional game
| addybojangles wrote:
| Silly nice brain teaser
| BiraIgnacio wrote:
| love it!
| tempestn wrote:
| That's actually a fun little puzzle.
| darepublic wrote:
| I won after four attempts. Pretty sure it was perfect play so yes
| white has forced win
| sdthjbvuiiijbb wrote:
| Yeah. I think 1. N4 leads to a white win. It's fairly easy to
| verify that a black rook move will lead to a white win (1...R5
| 2. R2 and 1...Rx4 2. Rx4 N5 3. Rx5#). So the critical line is
| 1. N4 N5, but then 2. Nx6+ K7 3. R4 also leads to a win:
| 3...Kx6 4. K2 K7 5. Rx5# and 3...N3+ 4. K2 N5 5. N8 Kx8 6.
| Rx5#.
|
| There are probably other ways to win too.
| hart_russell wrote:
| I don't know why this is stalemate: N4 N5, N6 K7, R5. Wouldn't
| rook have the king in checkmate?
| _air wrote:
| Black has no legal moves because of the knight but they aren't
| in check
| Scarblac wrote:
| The rook doesnt attack the king because N6 is in the way.
|
| So black is not in check and has no legal moves, so stalemate.
| superxpro12 wrote:
| Isnt that a forced move to K8? The king is forced to take N6
| or move to K8, either of which results in a capture.
|
| Isn't this the definition of checkmate, not stalemate?
| non- wrote:
| King isn't allowed to move to a square that would put him
| in check, so there are no legal moves available. Chess
| rules.
| systoll wrote:
| The relevant rule from standard chess:
|
| > Leaving one's own king under attack, exposing one's own
| king to attack and also 'capturing' the opponent's king are
| not allowed.
|
| N6 and K8 both expose the black king to attack, so black is
| not allowed to make those moves. And with no other options,
| black has no legal move.
|
| And since black isn't in check where they are right now -
| that's a stalemate.
| hackyhacky wrote:
| If you enjoyed this, you might like Mind Chess, which can be
| played without a board and pieces [1]:
|
| Consider Mind Chess. Two players face each other. One says
| "Check." The other says "Check." The first says "Check." This
| continues until one of them says, instead, "Checkmate." That
| player wins -- superficially. In fact, the challenge is to put
| off checkmate for as long as possible, while still winning. This
| may be better stated: you truly win Mind Chess if you call
| "Checkmate" just before your opponent was about to.
|
| [1] http://www.eblong.com/zarf/essays/mindgame.html
| anyfoo wrote:
| Which reminds me that I just lost the game.
|
| I also lost the game not too long ago, but before that, I think
| I didn't actually lose it for a decade of more? And losing it
| wasn't even because it was mentioned anywhere, I genuinely just
| thought of it by myself, after forgetting about it for so long.
|
| So my sincerest apologies if my comment just made any readers
| lose their long streak in the game.
| mckirk wrote:
| Damnit, I am pretty sure I had a few-year-streak going until
| just now. Welp, off to the grind again, I suppose.
| lamasery wrote:
| I've lost it _a lot_ lately, for some reason, after what I
| suppose was my third multi-year victory streak.
|
| Like, five or so losses this year.
| djsavvy wrote:
| Same here, oddly enough, and every time besides this one
| was without anyone else mentioning it.
| anyfoo wrote:
| I think once you lost the game once, it's much easier to
| lose it again relatively shortly after. It takes some
| long term distraction (and nobody mentioning it) to
| forget about it again.
| jaeh wrote:
| damn. multiyear streak ruined. i even managed to forget i was
| playing.
|
| i just lost the game.
| shmeeed wrote:
| Nah, I won't be fooled again. I won a long time ago and never
| looked back.
|
| https://xkcd.com/391
| edanm wrote:
| Yep, just lost after I think >5 years. But not because of
| your comment, because of GP comment.
| stavros wrote:
| Wait, how is the "put off checkmate" objective scored? Turns
| before checkmate? Or what?
|
| Is it just a joke?
| tylervigen wrote:
| I have never played it, but I could imagine a scoring
| mechanism that would make it interesting, and perhaps is
| implied by the rules:
|
| The score value starts at 1. Every additional "check"
| multiplies the score value by 2 (so 2, 4, 8, 16...). The
| first player to say "checkmate" receives the score. Track
| your summed score between games; the player with the highest
| overall score at any given time is "winning."
| zadikian wrote:
| It only works if there are more than two players
| zeroonetwothree wrote:
| Isn't the optimal strategy just to say "checkmate"
| immediately? That dominates anything else.
| hackyhacky wrote:
| That would be the equivalent of spawn camping.
|
| https://en.wikipedia.org/wiki/Camping_(video_games)
| hackyhacky wrote:
| The sibling comment proposed a possible scoring mechanism
| which might result in enjoyable gameplay, but I think the
| bigger point (for me, at least) is the Mind Chess represents
| a _reducto ad absurdum_ of the strategy game genre. It
| eschews as many rules as possible, leaving you only with the
| goal of knowing your opponent 's mind. So Mind Chess is more
| of a thought exercise.
| contraposit wrote:
| The Search for the Longest Infinite Chess Game
|
| https://youtu.be/b-Bb_TyhC1A
| bombcar wrote:
| It's similar to the 2-minute version of _Diplomacy_ - get
| everyone together and the second sneakiest bastard wins;
| because nobody will let the sneakiest bastard win.
| traderj0e wrote:
| Speaking of games without pieces, it's hard to develop one for
| only 2 players, but I've tried:
| https://news.ycombinator.com/item?id=43110448 (yes that is my
| alt account, sorry but I forgot my password)
| CGMthrowaway wrote:
| Sounds like a dating game. "Delay texting her back or
| expressing your feelings as long as possible, until just the
| moment before she will give up on you"
| benleejamin wrote:
| And if you like Mind Chess, you might enjoy Mornington
| Crescent, which has a similar flavor to it! [1]
|
| [1] https://www.youtube.com/watch?v=lziCsPmlbZI
| sjdv1982 wrote:
| Zugzwang!
| hypendev wrote:
| Don't know when was the last time I had so much fun with chess.
| Quite intuitive, clicked on the first click.
|
| Would enjoy so much if there were more of these, feels like an
| obligation-free chess puzzle.
| aktenlage wrote:
| Very cool. Reminds me of 1D Pacman:
| https://abagames.itch.io/paku-paku
| wes-k wrote:
| I love this! Such a simple game with a fun level of skill. High
| score 17485 feels pretty good (edit: Oh! Low power mode on the
| computer makes the game run slow, thus much easier to get crazy
| high scores).
|
| Reminds me of SFCave and Nanana Crash for the simplicity and
| surprising replay ability.
|
| https://megami.starcreator.com/nanaca-crash/
|
| (Failing to find an online version of SFCave a.t.m :'()
| aaaasmile wrote:
| Very cool!
| topce wrote:
| I went in other direction ;-)
| https://topce.github.io/chess960x32/
| Dante77711 wrote:
| Nice, fun and interesting! :)
| hfnjdbekwbiw wrote:
| Hello
| chedoku wrote:
| If you like 1D chess, you'll probably like other chess-themed
| puzzles as well: https://chedoku.com/blog/chessPuzzles
| tromp wrote:
| 1D Go is also interesting and doesn't require any change in rules
| or starting position. TIL that it is known as Alak [1]. One of
| the open problems in our Combinatorics of Go paper [2] is whether
| you can play a game that goes through all possible legal 1xn
| positions for any n>2, which we were only able to verify up to
| n=7.
|
| [1] https://senseis.xmp.net/?Alak
|
| [2] https://tromp.github.io/go/gostate.pdf
| Computer0 wrote:
| I was expecting a blog post regarding Iran strategy...
| MinimalAction wrote:
| I love chess! This version was fun too.
|
| If 1. Rx6,it is stalemate. So it must be 1. N4 N5. Then we could
| proceed with, 2. Nx6+ K7. Now, if you capture the knight (Rxe),
| it is stalemate again. So sacrifice the knight, 3. R4 Kx6 so that
| you force black to zugzwang with 4. K2 K7, and finally, 5. Rx5#
| slopinthebag wrote:
| I was confused why 3.R2 is drawing, but not 3.R4 since black can
| check with the knight either way, but it's fairly obvious in
| hindsight - if black checks instead of capturing, you don't take,
| you go K2 and force black into zugzwang. Clever.
| frunkp wrote:
| Those who play go may enjoy the variants:
| https://www.govariants.com/variants/rules-list Tetris is a fun
| one to try!
| sillyfluke wrote:
| I honestly thought this post was going to be about the Iran war.
| jibal wrote:
| N4 N5 Nx6+ K7 R4 Kx6 R2 (or K2) K7 Rx5#
| MagicMoonlight wrote:
| Why does it end in a stalemate if all my pieces are alive and
| they have none? That's not a stalemate, I can move freely and get
| them.
| chris_va wrote:
| In chess they cannot move onto a spot that would put them in
| check. If they can make no legal moves, it's a stalemate.
| dargscisyhp wrote:
| That is a standard rule in chess. If your opponent has no legal
| moves (i.e. no way to move without moving his king into check)
| and is not currently in check, it is considered stalemate,
| which is a draw.
| jpablo wrote:
| https://en.wikipedia.org/wiki/Stalemate#History_of_the_stale...
| gcheong wrote:
| Minor typo: assming -> assuming :)
| Keyframe wrote:
| This is stupid. I like it!
| dwa3592 wrote:
| I am ashamed to admit that i could not solve that even though i
| consider myself a decent player.
| keeganpoppen wrote:
| just work backward from the moves it allows you to make-- it
| tells you when it's hopeless, so thus if it lets you move,
| you're onto something. took me like 9 or 10 tries easily.
| keeganpoppen wrote:
| that took me way longer than i thought it would, but made me all
| the happier for it
| uvdn7 wrote:
| This is something AI would never take away from us.
| Nevermark wrote:
| I thought for sure this article was going to be political
| commentary!
|
| (I would pay a lot for some fat 1500 page, leather-bound tome of
| wisdom and anecdotes about historical foot guns, by Carl von
| Clausewitz, titled "1D Chess". And it's inevitable multi-
| authored, Harvard-published much thicker contemporary-world
| sequel.)
| freetime2 wrote:
| I tried and failed a couple times before looking at the hint. And
| then I had to ask ChatGPT to explain the hint because I didn't
| understand chess notation. But with all of that out of the way, I
| am now winning 100% of my matches and feel it's not an
| overstatement to call myself a 1D chess grandmaster.
| j2kun wrote:
| How often are you playing as black?
| freetime2 wrote:
| As often as the system decides that I should play as black.
| SV_BubbleTime wrote:
| Ha. I thought mine was broken on iPhone for a second.
| chatmasta wrote:
| Wow, Trump's job is harder than I thought.
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(page generated 2026-04-10 23:00 UTC)